1. Field
The present general inventive concept relates to a switching-mode power supply (SMPS) having an overvoltage cutoff function, and a method of cutting off an overvoltage and an image forming apparatus using the SMPS, and more particularly, to an SMPS for an image forming apparatus which may minimize and/or prevent an overvoltage and damage to the circuits in the SMPS and the image forming apparatus when a voltage higher than a rated voltage of the SMPS is supplied to the SMPS. The present general inventive concept also relates to a method of cutting off an overvoltage and an image forming apparatus and/or electronic device including the SMPS.
2. Description of the Related Art
A switching-mode power supply (SMPS) refers to a device that transforms an alternating-current (AC) voltage supplied from an external power supply source by using a transformer and outputs a direct-current (DC) voltage appropriate for an electronic product. An SMPS is more efficient, more durable, smaller, and lighter than a linear power supply.
Since an image forming apparatus, such as a printer or a copier, requires a power supply having a simple structure, a small size, and a stable power supply function, an SMPS is often used.
While South Korea uses an AC voltage of 220 V at 60 Hz as a standard voltage, other countries use various standard voltages according to their actual conditions. Although some countries use voltages of 100 V, 127 V, and 140 V, many countries use a voltage of 110 V or 220 V. In South Korea, an AC voltage of 220 V at 60 Hz is supplied to each household, and thus, most electronic products, such as an image forming apparatus, are only for 220 V or for both 110 V and 220 V.
An image forming apparatus receives an AC voltage from the outside and transforms the AC voltage into a DC voltage to be used therein. Such transformation occurs in an SMPS. Since parts in an SMPS vary according to an AC voltage input from the outside, if the AC voltage applied from the outside is higher than a rated voltage of the SMPS, the parts in the SMPS may be damaged, thereby leading to product liability (PL).
When an overvoltage is applied to an SMPS, a fuse of an AC power input terminal has blown by using a low-voltage varistor in order to avoid PL.